Abstract
Background: Musculoskeletal diseases with painful reflex muscle spasm have a high prevalence. Because of reflex muscle spasm, muscle relaxants are frequently used either alone or in combination with analgesics. Eperisone inhibits voltage-gated sodium channels in brain stem and tizanidine acts on imidazoline and α2-adrenergic receptor to relax muscle spasm and relieves pain. The development of sedation seems to be the major limiting factor in the use of muscle relaxants for treatment as they can affect daily activity and decrease working capability.

Aims and Objectives: The present trial conducted to evaluate the effect of eperisone and tizanidine on visual and auditory reaction time.

Materials and Methods: This was a prospective, double-blind, parallel group, randomized clinical trial. A total of 115 patients were randomized into two groups. Patients in Group A received tablet eperisone 100 mg and patients in Group B received tablet tizanidine 2 mg for 7 days. Primary outcome measures were changed in visual and auditory reaction time from baseline to day 7. Secondary outcome measure of the trial was change in the visual analog scale (VAS) is the most common research tool used to measure pain. VAS score of the sedation from baseline to day 7.

Results: On day 7, the difference in visual reaction time in Group A and B was 0.014 and 0.077, respectively, and this difference is statistically significant (P = 0.029). Difference in Auditory reaction time on day 7 in Group A and B were 0.007 and 0.091, respectively, and it is statistically significant (P = 0.004). There was increase in sedation score in Group B by 0.34 and it is statistically significant (P = 0.015).

Conclusion: Tizanidine increases visual and auditory reaction time and sedation which is not seen with eperisone. Eperisone is a preferred alternative for muscle relaxation to avoid these effects.

Key words: Muscle Spasm; Eperisone; Tizanidine